Process for improving paper strength

Abstract

The present invention provides a process for preparing a paper or paper board of improved strength which comprises the steps of i) providing a cellulosic thick stock, ii) diluting the thick stock of step i) to form a thin stock, iii) draining the thin stock of step ii) on a wire to form a web, and iv) drying the web of step iii) to form paper or paper board, wherein the cellulosic thick stock of step (i) comprises organic polymeric microparticles, as well as paper obtainable by above process.

The invention claimed is: 
     
       1. A method for improving the strength of paper or paper board comprising:
 adding anionic organic polymeric microparticles into a thick stock, 
 wherein the anionic organic polymeric microparticles are formed from a composition comprising at least one acrylic anionic monomer and at least one acrylic non-ionic monomer, 
 wherein the acrylic anionic monomer is at least one of (meth)acrylic acid, 2-acrylamido-2-methyl-1-propanesulfonic acid, or salts thereof. 
 
     
     
       2. The method of  claim 1 ,
 wherein the acrylic non-ionic monomer is at least one of (meth)acrylamide, an N—C 1-4 -alkyl (meth)acrylamide, an N,N-di(C 1-4 -alkyl)(meth)acrylamides, or a C 1-4 -alkyl(meth)acrylamides. 
 
     
     
       3. A method of improving the strength of paper or paper board comprising:
 i) providing a cellulosic thick stock, 
 ii) diluting the cellulosic thick stock of step i) to form a thin stock, 
 iii) draining the thin stock of step ii) on a wire to form a web, and 
 iv) drying the web of step iii) to form paper or paper board, 
 wherein the cellulosic thick stock of step i) comprises anionic organic polymeric microparticles, 
 wherein the anionic organic polymeric microparticles are formed from a composition comprising at least one acrylic anionic monomer and at least one acrylic non-ionic monomer, and 
 wherein the acrylic non-ionic monomer is at least one of an N—C 1-4 -alkyl (meth)acrylamide, an N,N-di(C 1-4 -alkyl)(meth)aerylamides, or an C 1-4 -alkyl(meth)acrylamides; and 
 the acrylic anionic monomer is at least one of (meth)acrylic acid; 2-acrylamido-2-methyl-1-propanesulfonic acid; or salts thereof.